/*
 * Copyright (c) Kumo Inc. and affiliates.
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <melon/auto_timer.h>
#include <melon/portability/gtest.h>

using namespace melon;
using namespace std;

struct StubLogger {
    void operator()(StringPiece msg, std::chrono::duration<double> sec) {
        m = msg.str();
        t = sec.count();
    }

    static std::string m;
    static double t;
};

std::string StubLogger::m = "";
double StubLogger::t = 0;

struct StubClock {
    typedef std::chrono::seconds duration;

    static std::chrono::time_point<StubClock> now() {
        return std::chrono::time_point<StubClock>(std::chrono::duration<int>(t));
    }

    static int t;
};

int StubClock::t = 0;

TEST(TestAutoTimer, HandleBasicClosure) {
    auto logger = [](StringPiece mesg, auto sec) {
        return StubLogger()(mesg, sec);
    };
    StubClock::t = 1;
    // Here decltype is needed. But since most users are expected to use this
    // method with the default clock, template specification won't be needed even
    // when they use a closure. See test case HandleRealTimerClosure
    auto timer = makeAutoTimer<decltype(logger), StubClock>(
        "", std::chrono::duration<double>::zero(), std::move(logger));
    StubClock::t = 3;
    timer.log("foo");
    ASSERT_EQ("foo", StubLogger::m);
    ASSERT_EQ(2, StubLogger::t);
    timer.logFormat(fmt::runtime("bar {}"), 5e-2);
    ASSERT_EQ("bar 0.05", StubLogger::m);
    ASSERT_EQ(0, StubLogger::t);
}

TEST(TestAutoTimer, HandleBasic) {
    StubClock::t = 1;
    AutoTimer<StubLogger, StubClock> timer;
    StubClock::t = 3;
    timer.log("foo");
    ASSERT_EQ("foo", StubLogger::m);
    ASSERT_EQ(2, StubLogger::t);
    timer.logFormat(fmt::runtime("bar {}"), 5e-2);
    ASSERT_EQ("bar 0.05", StubLogger::m);
    ASSERT_EQ(0, StubLogger::t);
}

TEST(TestAutoTimer, HandleLogOnDestruct) { {
        StubClock::t = 0;
        AutoTimer<StubLogger, StubClock> timer("message");
        StubClock::t = 3;
        timer.log("foo");
        EXPECT_EQ("foo", StubLogger::m);
        EXPECT_EQ(3, StubLogger::t);
        StubClock::t = 5;
    }
    ASSERT_EQ("message", StubLogger::m);
    ASSERT_EQ(2, StubLogger::t);
}

TEST(TestAutoTimer, HandleRealTimerClosure) {
    auto t = makeAutoTimer(
        "Third message on destruction",
        std::chrono::duration<double>::zero(),
        [](StringPiece mesg, auto sec) {
            KumoLogger<KumoLoggerStyle::PRETTY>()(mesg, sec);
        });
    t.log("First message");
    t.log("Second message");
}

TEST(TestAutoTimer, HandleRealTimer) {
    AutoTimer<> t("Third message on destruction");
    t.log("First message");
    t.log("Second message");
}

TEST(TestAutoTimer, HandleMinLogTime) {
    StubClock::t = 1;
    AutoTimer<StubLogger, StubClock> timer("", std::chrono::duration<double>(3));
    StubClock::t = 3;
    // only 2 "seconds" have passed, so this shouldn't log
    StubLogger::t = 0;
    ASSERT_EQ(std::chrono::duration<double>(2), timer.log("foo"));
    ASSERT_EQ(std::chrono::duration<double>::zero().count(), StubLogger::t);
}

TEST(TestAutoTimer, MovedObjectDestructionDoesntLog) {
    const std::vector<std::string> expectedMsgs = {
        "BEFORE_MOVE", "AFTER_MOVE", "END"
    };
    int32_t current = 0;
    SCOPE_EXIT {
        EXPECT_EQ(3, current);
    };

    auto timer = [&expectedMsgs, &current] {
        auto oldTimer = melon::makeAutoTimer(
            "END",
            std::chrono::duration<double>::zero(),
            [&expectedMsgs, &current](
        StringPiece msg, const std::chrono::duration<double> &) {
                EXPECT_EQ(expectedMsgs.at(current), msg);
                current++;
            });
        oldTimer.log("BEFORE_MOVE");
        auto newTimer = std::move(oldTimer); // force the move-ctor
        return newTimer;
    }();
    timer.log("AFTER_MOVE");
}
